1. Field of the Invention
The present invention relates to an engine system, in particular, relates to an engine system for a vehicle, which uses an engine as one of driving sources, and an operating method therefor and an engine starting apparatus.
2. Description of the Related Art
In general, the engine of a vehicle is started by activating a starter motor using a battery as the power source, and after combustion has once commenced, the engine is used as a drive source for propelling the vehicle and for operating various auxiliary machine. One example of auxiliary machines provided in the vehicle is, for example, a compressor for an air conditioner, a pump for a power steering, a oil pump for an automatic transmission, a vacuum pump, for a brake system and the like.
Conventionally, in such a vehicle using the engine as an only drive source for the auxiliary machine, the auxiliary machine could not driven while the engine is stopped.
However, recently with the purpose of improving fuel efficiency and reducing CO2, based on a view point of so called energy conservation, attention is being paid to a hybrid vehicle, which stops the engine in a light load region or while the vehicle is stopped and which travels by motor by regenerative electric power or electric power generated while the engine is operating.
Moreover, an idle stop vehicle has been proposed recently, which automatically stops the engine while the vehicle is stopped and stops the fuel injection while idling in order to thereby improve the fuel consumption and also reduces CO2.
In these hybrid vehicle and idle stop vehicle, since the engine is stopped while the vehicle is stopped, for example while waiting for a traffic signal or during a traffic jam or the like, even while the engine is stopped it is still necessary to operate the air conditioner to continue the air-conditioning the interior. Moreover, in a hybrid vehicle, while travelling by motor with the engine in the stopped condition, it is still necessary to operate no only the air conditioner but also all of the auxiliary machines necessary for travelling.
A method of operating an air conditioner in a hybrid vehicle while the engine is stopped is disclosed, for example, in Japanese Patent No. 3180506. In this method, an auxiliary motor is installed in the compressor of an air conditioner, for driving the compressor, and when the remaining battery charge is high, the compressor is driven by the auxiliary motor, while when the remaining battery charge is low, the engine which is linked to the operation of the air conditioner is shifted from a stopped condition to a drive condition, so that the compressor of the air conditioner is driven using the engine as the drive source.
However, installation of an auxiliary motor in the compressor with the sole purpose of driving the compressor increases the number of parts and also increases the product cost, and thus undesirable.
Furthermore, in Japanese Unexamined Patent Application, First Publication No. 2000-120463, there is disclosed an engine system where an engine starting motor is connected via a planetary mechanism and a belt and pulley to an engine and auxiliary machines, and a clutch is provided with the engine output shaft so that it is possible to switch connection or disconnection of the transmission of the torque from the motor to the engine. According to this engine system, by disconnecting the clutch and allowing only torque transmission from the motor to the auxiliary machine, the auxiliary machine can be driven even when the engine is stopped.
However, provision of a clutch with the engine crank shaft increases the length in the direction along the output shaft of the engine system and causing a big problem when there is a restriction on the engine installation space.
Moreover, in order to switch from starting the engine by the motor to driving of the auxiliary machine by the motor, switching of the clutch mounted to the engine output shaft, and switching of the brake provided with the ring gear of the planetary mechanism mounted to the motor must be performed at the same time, which result in causing the problem that construction becomes complex and the control operation thereof becomes complicated.